The present invention relates to printing presses and more particularly to a device for decelerating signatures in the folder section of a printing press.
In web fed printing presses, a continuous web of paper is fed from an infeed roll, through various processing units, such as the print units, dryer, chill unit, slitters, folder, stackers, log bundlers, and print rolls, in order to produce a printed product. Typically, after the web has been printed and dried, it is folded and cut. When the web is cut, the individual products that result are referred to as signatures. Often, the folder delivers signatures faster than they can be processed by the succeeding processing unit. Therefore, it is necessary to slow the signatures"" speed. It may also be preferable to place the signatures into a shingled formation wherein the leading edge of one signature overlaps the trailing edge of the signature preceding it.
Known methods and apparatus for slowing down signatures include fan wheels, as described in U.S. Pat. Nos. 5,112,033, 5,180,160 and 4,925,179, each of which is incorporated herein by reference. Generally, signatures are delivered from a folder to a press delivery conveyor by a fan wheel. The fan wheel includes a plurality of fan blades that form fan pockets for receiving the signatures from the folders as the fan wheel rotates. The signatures may be stripped from the fan wheel by a stripper and may be transferred onto, for example, a delivery conveyor. However, there are problems associated with the use of fan wheels such as marking, dog-earing and bottom-of-pocket rips or dents.
It is an object of the present to provide an apparatus that decelerates and shingles signatures including: a tape system adapted to receive the signatures from a folder, the tape system increasing a speed of the signatures; a first conveyor belt disposed adjacent to the tape system, the first conveyor belt receiving signatures from the tape system, the first conveyor traveling at a speed slower than the tape system; a first knock-down wheel rotatably mounted above the first conveyor and in rolling engagement with the first conveyor, the knock-down wheel being adapted to force signatures into conformance with the speed of the first conveyor; a second conveyor belt disposed adjacent to and downstream from the first conveyor belt adapted to receive signatures from the first conveyor, the second conveyor traveling at a slower speed than the first conveyor, and a second knock-down wheel rotatably mounted above the second conveyor and in rolling engagement with the second conveyor, the second knock-down wheel adapted to force the signatures into conformance with the speed of the second conveyor.
Using the device according to the present invention, cut and folded signatures are decelerated and placed into a shingled stream. The shingle spacing may be adjusted in subsequent stages. The device uses a system of tapes and rollers, conveyors, knock-down wheels, and tracking drive. According to the present invention, signatures may be delivered from a folder to a conveyor system without entering into a fan wheel. Thus, a shingled delivery system comprising conveyors and knock-down wheels may be employed rather than a fan wheel or deceleration drum system, the cost of which may be prohibitive in certain applications.
According to the present invention, signatures are delivered by, for example, a tape drive system from the folder to a conveyor. The signatures are deposited onto a conveyor that is traveling more slowly than the tape drive system. The signatures may be contacted by and pressed into contact with the conveyor by knock-down wheels. In this manner, the signature is slowed down to travel with the more slowly moving conveyor belt. A series of conveyor belts and knock-down wheels may be used to achieve a desired amount of deceleration using incremental steps. Such an incremental approach may be beneficial in achieving a desired deceleration without abrupt decelerations that could damage and mark the signatures. If too great a deceleration is attempted with, for example, a single stage knock-down wheel/conveyor system, the signature may become marked or damaged. Thus, high speed printing systems may benefit by using multiple conveyor/knock-down wheel arrangements.
Other objects, advantages, and characteristics of the present invention will become apparent in view of the description and accompanying drawings that follow.